Transmission system



sept. 2, 1924. mouse R. l. D. NICOLL TRANSMISSION SYSTEM Filed Feb. 2o.` 1920 UHIIIHU IIIIIIOIIIH Patented Sept. 2, 1924.

UNITED STATES PATENT OFFICE.

ROBERT I.D. NICO'LI, OF SUMMIT, NEW JERSEY, ASSIGNOR. TO WESTERN ELECTRIC COMPANY, INGORPORATED, OF ,NEW YORK, N. Y., A'GORIPORATION 0F NEW YORK, i

j y: TRANSMISSION svs'rnlvr.

Application filed February 20, 1920.

T0 all whom t may concern.'

Be it known that '1, ROBERT I. D. NIcoLL, a citizen of the United States, residing at Summit, in the county of Union and State of New Jersey, have invented` certain new and useful Improvements in Transmission Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to transmission systems and more particularly to transmission systems employing means for signaling.

In telephonie transmission systems it has been the practice to employ repeaters or amplifiers for improving the efiiciency of the transmission between widely separated stations. In one system of this nature, a link circuit including the amplifying means, is used at a central office for interconnecting the terminals of the line circuits leading to the distant stations to thereby include the repeater or amplifier in the communication p channel established between the separated stations. The characteristics of the line circuits vary considerably and in order to insure the properk operation of a telephone repeater of the usual type, it has been the practice to provide a network or artificial balancing transmission line for cooperative association with each line circuit when the repeater is employed. It is also necessary to provide means in the link circuit cooperating with the associated line circuits to control suitable signaling and switching means.

In one system of this nature, it has been the practice to employ separate switching terminals and conductors connected to the line circuits and link circuits to associate the proper artificial lines with the amplifying means.

lt is the object of this invention to provide a simplified and improved system of this character in which the eXtra conductors and associated switching terminals heretofore required for the association of the artil iicial line are eliminated by obtainingV one signaling and two transmission paths from the three conductors.

In order to attain this object, in accordance with a feature of the invention, repeating coils are introduced in the artificial transmission lines and therassociated line circuits which coils are interconnected with the single line terminal so that one transmission circuit comprises two conductors and a Serial No. 360,232.

winding of one repeating coil, while another transmission circuit comprises the other coni ductor, a winding of the other repeating coil and the simplexed conductors of the former circuit. A signaling path is also simplexed upon the latter circuit and comprises the three conductors in parallel. y l This and other features, not specifically mentioned above, will clearly appear from the following specification and accompanying drawing which shows a suificient portion of a telephone exchange system to properly illustrate the inventio 1n the drawing, two line circuits A and C extending to distantstations (not shown) terminate in yjacks 1 and 20 respectively, at a central oflice. The line circuit A is provided with the usual line lamp 2, the line relay 6,

and the cut-off relay 5, while the line circuit C is provided with a line lamp 22, a line re lay 26 and a cut-olf relay 25. balancing lines of any usual and'well-known type diagrammatically illustrated by the rectangles NA and NC are also provided for the line circuits A and C respectively. Repeating coils 3 and 4 are vincluded between the ack 1 and the conductors of line circuit A and of artificial line circuit NA respecn tively, while similar repeating coils 23 and 24A are included in asimilar Vrelation between the jack 20 and the line circuit C and 'the artificial line circuit NG respectively. A link circuit B of any usual. type equipped with any well-known telephone repeater or ganization, such as that disclosed in the United States patent to Toomey, No. 1,1107,- 604e of February 21, 1922, is provided at the central office and terminates in plugs v10 and 19 for association with the jacks 1 and 20 respectively. Therepeater organization is not shown in detail since it is unessential to the proper understanding of the inventionand is therefore diagrammatically represented by the rectangle R., Repeating coils 13 and 14 are introduced between the repeater R and the plug 10, while repeating coils 15 andlG are included between the repeater R and the plug 19. Drops .11 yand 17 are employed to provide the usual Balancing resistances 7, 12, 18 and 27 are ineluded in the various sleeveconduc-tors to properly adjust the resistances thereof.

It is .thought that the invention may be Artificial F supervisory` signals.

more easily; comprehended from the follow-wY ing:r description of the operation of the system showniontlie `l`drawing..

Signaling currentbeing received over the conductors of line A and flowing through eratessaidre/lay. 4Lamp 2-is thereby lighted and relay 6 locked over obvious circuits. The operator, upon observing the lrlighted condition of lamp 2, inserts plug 10 into ack 10 1, operating the cuto`l'"re"lay"5 overa circuit catenin@ from battery to the mid-point of 4theleftUhfand winding otrepeating 'coil '14, l"and @thence-Kin fp arallel onej ath `incl`uding *the ilo'wer'half' offs'u'ch Winding, the vfresist- "ance A"'12,thefsleeve contacts' of plug' 10 and fj'a'ck `1',"t"he` resistance, the lower half Aof the "rightlhand"winding ofA repeating coil 4;' and the Winding of"cut`loiii"'1"e'lay' 5 tof'gro'und, "while Athe other pathfjextends through the per `r^rrhalf of the left-hand `windi`ngfof A peatingf'coil x"111 vvto theinjidpointoftle "liands'fwinding'ofi'epeatingcoil' 13, land thence inl parallel *through the upper and lower halves of such y'wi-i1ding,"thetip and ijifnfgcontacts of v'plug 1'0 and 'jackf1`,= andV the upper" and low/erf halvesl of* the. rig1a.-hand "windin 'lofrepating `coil`^13to theinidfploint; o "such," winding, Eand thence through i the l upper half ofE the right-handv 'windind ofrepatin'gl'coilfa" to t'hey 'midLpoint of suoli "Winding where? 'it joins'the' first` traced path. The' `balancing yresistan''ces "7 and 12 are iniolii'de'dl tofinsure'tll'iatthe parallel pat-hsA vare of equalf'r'esistance. Relayt 5, iinoperating, H*'eleas`es"r,el`ay; 6* disconnecting theV leftdiand "winding tlhereof frointhe linefconduct'ors "asfivell as'eXtingLlishingline lanip 2. The

sperati, apenI aseeaaiaiag falen-gh ai@ *Tnediiunof a listening key' (not shown) that "'25 Y-`1nayf tbe' traced"E froni battery toftlie niidpoint ofi` ithe" lrighthandi wirf-ding" of; repeat- 'coil ixandt thence iny parallel,y one vpath j 'eatencling.'v through l the "upper 4`l'lal'l5 of such ""yvinding, the balianc'iiig'A resistance the sleeveioontactsfofplugl19andjack 20, the l sistanced" 27, u'the lowerhalf or' thellei'thand d iigfofrepeating coil 24,2' and' the windfrlay 25 to"ground,"while theother tends-through they lower half `of the and winding f of "the "repeating 'coil A y ldlpointfof theright-handwind- Yi ng"`ofirepeating'coilfloiand thencein pari 1"'tliiou`gh the halves 'of `such "winding, "pid rM glcontacts of/'plug 19"A and `'ack dpthehallvsof the Lleft-"handwinr ing peatingc'oil23 tothe'inidpoint of such "fwl'id" iandt ence `tliroigh "t'fhe' upper/half i l'" "d winding ofiepeatingcoil/Q; ointfofq winding ifvhere it sti' llvdfpath. ""Balaricing'7re a Hthe'leftA-l'iand winding of line relay 6 op` sistances 18 and 27 are adjusted to compensate ".t'ordiiferenc'es in the' resistances uof the parallel paths.

Thereupon, conversational channels are established between the widely separated stations connected with ltheline circuits A and G. As is the usual practice, the .talking' currents transmitted from the output circuit of the repeater R in each case divide, *ap'ortion being f transmitted over the connected line circuit to the distant station and a substantially equal portion -passingover the "associated artificial `line circuit. Thus lthe 'talking currents passing to `line circuit A ir'are induced "through the repeating coil 13 linto 'afcllosed `circuit including the tipI and "ring" contacts of plufgl@ andfjack l-fand the -rigilitf-han'd winding of repeating coill 3i'and, by virtue of the latter-mentioned Ecoil, are 'indiuced'tothe line circuit A. However, the

ta'lkingl currents, inpassingl to the artificial lii'ie NA, are f induced Vby repeating coil 14 into i a closed Ycircuit "which lniay be' traced Heroin' the upper terminal of the "left-hand Y windingof repeating'coil 14, to theinidpointj of thef left-hand winding of' `'repeating coil *'13, and ltlience over parallel paths in- `clufding-thelupper and lower halves ofthe lett-hand winding'of repeating coil 13, the `ftipaiodring contacts l'of plug 10 and jack 1 :and the vupper and lower halves of the righthandwind'ig ofrepeatingcoil 3 to theinid` 'pointtof such winding, and thence through the "rightLhand winding of "repeating coil "4l and *resistance 17, Vthe'sleeve contacts of bjack -liand plugv 10A and. the resistance v12 'zito the' lower lterminal off| the" left-hand wind- Vielect/7e conductors l`connect"ed"'to "che sleevel 'contacts offisuch terminals. l

` Upon lthe' cessation of the'con've'r'sation, 'signa'ling current maybe" impressed upontlie "line circuitsi atthe distant stations "inf'the vfordiiiary" inanner, f'causing theoperation foi 'the drops lland '17*to providedisconnect signals whereupon theop'erator withdraws "'theiplugs 10l and19'ffroin the jacksliand 20 f respectively Eand l all apparatus -`restored `to y'normal Thus itiwillbe evident that theoonductors 4"leadingY tothe-"tip, ring and sleeve contact ofthe' plug and* ackwhen interconnected, areiitilizedtoiprovide twofcicuits oritalking 'of'l repeat-,ingr coil 14. In a similar niany ing current and one circuit for signaling current.

What is claimed is:

1. In a transmission system, three conductors interconnecting two points, repeating coils associated with two of the conductors at each point to form a series circuit for talking currents, another repeating coil at each point associated with the other conductor and connected to the mid-point of a winding of the first-mentioned repeating coil thereat to form another circuit for talking current-s and a circuit for signaling currents connected to the mid-points of the windings of said other repeating coils.

2. In a. telephone transmission system, a plurality of line circuits, artificial balancing line circuits therefor, a common three contact terminal for each line and its associated artificial line, a telephone repeating link circuit for interconnecting the lines and terminating at each end in three conductors, and cooperating means included in the link and line circuits to provide two circuits for talking currents and one circuit for signaling currents.

3. In a signaling system, a plurality of line circuits, artificial balancing line circuits therefor, a common three-contact terminal for each line and its associated artificial line, a telephone repeating link circuit for interconnecting the lines and terminating at each end in three conductors, and cooperating means included in the link and line circuits to provide two circuits for talking currents.

4t. In combination, a signaling line, a repeater therefor, a balancing network for said line, and a simplexed circuit connecting said network to said repeater.

5. In combination, a signaling line, a repeater, an artificial line and a three-terminal plug and a cooperating three terminal jack for connecting said repeater both to said artificial line and said signaling line, one of said three-terminal devices being normally connected to said lines, the other of said three-terminal devices being normally connected to said repeater.

6. In combination, a signaling line, a balancing network for said line, a repeater and a three-wire link circuit for connecting said repeater both to said line and said network, said repeater being connected to one of the other-mentioned devices by two of said wires in parallel, the electrical path being completed by the third wire, said repeater being connected to the remaining device by sai two wires acting in series.

7. In combination, a signaling line, a balancing network therefor, a repeater, a link circuit between said line and said repeater comprising two impedances, a connection between intermediate points of said impedances including a plurality of other impedances, means for associating one of said last mentioned impedances with said balancing network and means for associating one of said last mentioned impedances with said repeater.

8. `In combination, two transformers, connections between the terminals of the seoondary winding of one of said transformers and the terminals of the primary winding of the other of said transformers, a connection between the midpoint of said secondary winding and the midpoint of said primary winding, said last connection including windings of a plurality of other transformers, and a resistance in said third connection having a value depending upon the direct current resistance of the winding of one of said transformers.

9. In combination, two transformers, connections between the terminals of the secondary winding of one of said transformers and the primary winding of another of said transformers, a connection includin atransformer winding between the mi point of the secondary winding of the first trans former and the primary winding of the second transformer, and a source of signaling currents connected to the midpoint of the transformer winding in said third connection.

In witness whereof, I hereunto subscribe my name this 13th day of February, A, D. 1920.

ROBERT I. D. NICOLL. 

